Spark-plug



G. V. HARRIMAN.

SPARK PLUG. APPLICATION FILED DEC. 3. 191s.

151360,946. l Patented Nov. 30, 1920.

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SPARK-PLU@ Specification of Letters Patent.

Patenten nav, se, ieee.,

Application led December 3, 1918. Serial io. 265,105.

To all whom it may concern:

Be it known that l, GEORGE V. HARRIMAN, a citizen of the United States,residing in yNew York city, in the county of New York and State of NewYork, have invented certain new and Vuseful improvements in Spark-Plugs,of which the following is a specification.

My present invention relates to an iinprovement ire-plugs for use ininternal combustion engines, and the principal object of my invention,in addition to. providing a spark plug of great eliiciency, is toobviate short-circuiting of the spark plug due to the coating,parbOniZing, or bridging of the ignition points thereof., l

l attain this object by the device illustrated in the accompanyingdrawing, which is a sideview of my improved spark plug, partly invertical section, and in which similar numerals refer to similar parts,as related to my invention as set forth in this specification.

My improved spark plug comprises in its main elements or parts, a shellor bushing 1, and an insulator core generally denoted by 2, andpreferably made of porcelain.

The shell or bushing is chainbered to receive the insulator core 2, andhas a threaded lower exterior portion 3, for attachment to the cylinderof an internal combustion engine. and has an interiorly threaded upperportion Il, to receive a compressive threaded bushing hereinafter morefully described. The chamber of the shell or bushing l, below theinteriorly threaded portion 4, is vertical and terminates at its base inan inwardly extending ledge or flange 5, the vertical side of thechamber and the ledge or flange 5, forming alright angle, when viewed invertical cross-sec-` tion. The shell or bushing 1, has at its lower enda terminal wire 6, which is embedded or otherwise suitably fixed to the`the horizontal base or the shoulder are arranged to engage respectivelythe'vertical sides and the upper surface of the flange 5, of the chamberof the shell or bushing 1, and the downward extension 8, of theinsulator core is arranged to it closely the oriioe or opening at thebottom of the shell or bushing 1, the purpose being to prevent entranceof gases or matter into the chamber of the shell or bushing, or contactthereof with the insulator core 2.

The projecting end, or firing pin end 9, of the insulator core 2, is inlength exaggerated, that is. it is made longer than customarily used inspark plugs, to permit insertion thereof well into the ignition space ofthe engine cylinder, -with the ignition portion of the spark plug, andowing to the preventing of entrance ot` gases between the shell orbushing 1, and the insulator core 2, as above sta-ted, that when myspark plug is subjected to the high heats ofl ignition and the swirlingCyclonic action of heated gases, the porcelain portion of the plug isthoroughly scoured or' deleterious deposits, and that the surface of thetruncated cone shaped tiring pin end 9, does not become coated, andthere is no tendency to shortcircuit between the electrode or firing pinand up and through carbon deposits customarily formed thereon, to thebase of the shell or bushing 1.

The insulator core 2, is provided with a longitudinal duct 10. for acentral electrode or firing pin 11, which coacts with the terminal wire6, to forni a'sparking gap in accordance with the well known practice.rlhe tiring pin, 11, has a shoulder 12, which engages a ledge 13,located within the lower extremity oi the insulator core 2.

rlhe upper end 'of the liring-pin 11, has a thread 14:, to receive alock-nut 15, and the usual thumb-nut 16, whereby electrical contact maybe made.

A compressive exteriorly threaded bushing 17, is provided to engage theinteriorly threaded portion of the shell or bushing 1, and to receivethe insulator core 2.

A packing or gasket 18, is provided for the space formed by thediminished portion of the insulator core 2, above the shoulder 7 andbetween the interiorly threaded portion or the shell or bushing 1, thepacking oi' gasket being securely held in place by the compressivebushing 17, the inward curve of the shoulder 7, conducing the lil@tightness and serving as a thrust shoulder for maintaining the insulatorcore 2, in .it-s proper operative position.

The packing or gasket, 18, may be of any suitable material, such asasbestos.

In practice I have found that owing to the close contact respectively ofthe vertical sides and the horizontal bottom of the shoulder 7, of theinsulator core with the vertical sides and the upper surface of theledge of the chamber of the shell, and the close contact of the downwardextension 8, of the insulator core with the bottom opening or orifice ofthe shell, the lodgment of oil or carbon between these parts isprevented, and a starting point for a carbon bridge is eliminated. Andfurthermore, the packing 18, by compression of the bushing, 17, isforced inwardly and downwardly against the curved portion of theinsulator core 2, thereby to maintain the insulator core in operableposition.

In numerous trials of a plug made as herein set forth, I have found thatthe firing pin end of the plug of exaggerated length and ofsubstantially truncated cone shape, has' continued to operate for longperiods, without trouble due to short circuits formed by carbon, orvsoot bridges, or the like.

I claim:

A spark plug comprising a shell having means for engagement with aninternal combustion engine, and provided with a chambered interior openat top and bottom having a vertical side wall, and having an inwardlyextending ledge at the base of the shell at right angles to said sidewall, and having an arcing terminal at the bottom of said shell, aninsulator core partly contained in said shell and having a verticallysided shoulder with a horizontal base, said shoulder curving inwardly atits upper end to the diameter of the insulator core, and having adownwardly extending portion adjacent to and below said shoulder, andhaving a downwardly projecting end of truncated cone shape, a firing-pinarranged within the insulator core having an arcing terminal extendingfrom said truncated cone shaped end, and having a shoulder at the lowerend engaging the lower end of the insulator core, a compressing bushingfor engaging the upper interior of the shell and having a downwardextension of exterior diameter substantially the same as the diameter ofsaid shoulder, and having a longitudinal passage therethrough ofdiameter to engage closely the insulator core, there being space formedbetween the lower end of said bushing and the upper end of saidshoulder, a packing for said space, a locknut for the upper end of thefiring-pin, and means for electrical contact; said packing beingcompressed by said bushing to prevent passage of gas, and the inwardlycurving portion of the shoulder of the insulator core forming with thevertical side wall of the chamber of the shell an outwardly curvingbottom to the above mentioned space to force the packing inwardly anddownwardly when compressed against the insulator core to maintain theinsulator core in operable position in said shell.

GEORGE V. HARRIMAN. Witnesses:

W. L. MosELEY, MARTHA VoLz.

